1. Field of the Invention
The present invention relates to a document pressing apparatus for pressing a document at a specified image reading position, an image reading apparatus and an image forming apparatus with this document pressing apparatus.
2. Description of the Related Art
An image forming apparatus for forming an image on a sheet based on a document image includes an apparatus body for performing an image forming operation, a document pressing apparatus and an image reader. Generally, the document pressing apparatus is rotatably supported on one end of a housing of the image reader. A document set on a contact glass of the image reader is pressed at an image reading position by the document pressing apparatus and an image plane thereof is optically read.
In an image forming apparatus employing an electrophotographic process, a photoconductive drum is charged beforehand and a laser beam modulated based on image data of a document image is irradiated to the outer surface of this drum to form an electrostatic latent image. Subsequently, a developed toner image is transferred and fixed to a sheet. Here, if the document is lifted up from the image reader, the image plane cannot be accurately read. Accordingly, technology for providing a document pressing apparatus with a cushion member has been disclosed (see, for example, Japanese Unexamined Patent Publication No. H08-201935).
According to this prior art, the thickness of the cushion member is gradually increased with distance from a position of rotation of the document pressing apparatus. Thus, the lift of the document can be prevented over the entire surface at the image reading position.
However, according to this prior art, a degree of adhesion between the document pressing apparatus and the image reader is excessively high and it is difficult for a user to open the document pressing apparatus after the image plane is read. Further, if the user opens the document pressing apparatus with vigor, there is also a problem that the image reader sticks to the document pressing apparatus and is lifted up together.